Editorial for the Special Issue on Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume II

Wide bandgap (WBG) semiconductors are becoming a key enabling technology for several strategic fields of human activities [...].

A power conditioning system is designed and built using SiC MOSFETs as switching devices by Ma et al. in [8], which, by leveraging the excellent thermal and voltage capability of SiC MOSFETs, is suitable for grid-level energy storage systems based on vanadium redox flow batteries. A digitally controlled photovoltaic emulator based on an advanced GaN power converter is developed by Ma et al. in [10], whereas in [9], the driving requirements of SiC MOSFETs and GaN HEMTs are illustrated, and the driving circuits designed for WBG switching devices are surveyed.
In [11], Kim et al. demonstrate that InGaN/GaN MQW LEDs on Si substrates with an AlN buffer layer grown with NH 3 interruption show improved crystal quality and enhanced optical output compared to LEDs with conventional AlN buffer. On the sensing application side, AlN is exploited by Chiu et al. [12] to fabricate piezoelectric micromachined ultrasonic transducers that are used to build a high-accuracy time-of-flight ranging system. Nguyen et al. [13] investigate the sensing characteristics of NO 2 gas sensors based on Pd-AlGaN/GaN HEMTs at high temperatures, while Thalhammer et al. [14] describe a novel class of X-ray sensors based on AlGaN/GaN HEMTs offering superior sensitivity and the opportunity for dose reduction in medical applications.
On the advanced processing technique side, laser micromachining on the frontside of SiC and sapphire wafers and the conditions by which the degradation of the performance of GaN HEMT electronics on the backside can be avoided are investigated by Indrišiūnas et al. in [15]. A novel dual laser beam asynchronous dicing method is proposed by Zhang et al. in [16] to improve the cutting quality of SiC wafers.
Regarding the properties and growth of emerging WBG materials, a methodology to synthesize gallium nitride nanoparticles by combining crystal growth with thermal vacuum evaporation is proposed by Fathy et al. in [22]. AlN is explored as an ultra WBG material in three papers: annealing Ni/AlN/SiC Schottky barrier diodes in an atmosphere of nitrogen and oxygen is shown to lead to a significant improvement in the electrical properties of the structures by Kim et al. in [19]; the effect of high-temperature nitridation and a buffer layer on semi-polar AlN films grown on sapphire by hydride vapor phase epitaxy is studied by Zhang et al. [21]; and the thermal annealing of AlN films with different polarities and its impact on crystal quality are studied by in Yue et al. in [23]. The effect of the annealing temperature on the microstructure and performance of sol-gel-prepared NiO films for electrochromic applications is analyzed by Shi et al. in [17]. Solution-processed In 2 O 3 thin films and TFTs are fabricated, and the factors affecting the stability of these devices are investigated by Yao et al. in [18]. The electronic structure and the optical properties of Srdoped β-Ga 2 O 3 are studied by Kean Ping et al. [20] using DFT first-principles calculations.
I would like to take this opportunity to thank all the authors for submitting their manuscripts to this Special Issue and all the reviewers for their time and their fundamental help in improving the quality of the accepted papers.

Conflicts of Interest:
The author declares no conflict of interest.